Polymers containing units of carbon monoxide and one or more ethylenically unsaturated hydrocarbons are known in the art. Brubaker, U.S. Pat. No. 2,495,286, prepared such materials in the presence of certain free radical catalysts, e.g., organic peroxy compounds. British Pat. No. 1,081,304 produced such materials in the presence of alkylphosphine complexes of palladium. Nozaki extended the scope of the polymerization reaction to include various arylphosphine complexes of palladium, U.S. Pat. No. 3,689,460, and cyanide complexes of palladium, e.g., U.S. Pat. No. 3,835,123. Shryne et al described similar polymerizations in certain solvents such as hexafluoroisopropanol and m-cresol, U.S. Pat. No. 3,984,388. Published European Patent Application No. 0,121,965, published Oct. 17, 1984, describes the polymerization of carbon monoxide and unsaturated hydrocarbons in the presence of a compound of palladium, cobalt or nickel, an anion of a non-halogenic acid having a pKa less than 2 and a bidentate ligand of phosphorus, arsenic or antimony. Copending U.S. patent application Ser. No. 935,431, filed Nov. 26, 1986, discloses the polymerization of carbon monoxide and certain primary olefins in the presence of bidentate ligands of nitrogen.
When the polymer product is a linear alternating polymer of carbon monoxide and unsaturated hydrocarbon, the polymer is referred to as a polyketone. Such materials are premium thermoplastics having a variety of known uses. One disadvantage of some polyketones, e.g., copolymers of carbon monoxide and ethylene, in some applications is a relatively high melting point. This disadvantage can be overcome through addition of a plasticizer to the polyketone, if a suitable plasticizer is available, but also through the incorporation in the polymer chain of a second hydrocarbon monomer. The resulting terpolymers will generally have melting points below analogous copolymers.
Production of terpolymers of carbon monoxide, ethylene and a primary ethylenically unsaturated hydrocarbon, e.g., an ethylenically unsaturated hydrocarbon having only one hydrocarbyl substituent on a carbon atom of the ethylenic unsaturation such as propylene or octene-1, is accomplished with relative ease, Published European Patent Application No. 0,121,965. More difficult is encountered if terpolymers are desired which are formed from carbon monoxide, ethylene and a secondary olefinically unsaturated hydrocarbon. A secondary ethylenically unsaturated hydrocarbon is one in which two hydrocarbyl substituents are attached to a carbon atom of the ethylenic unsaturation, e.g., isobutylene. It would be of advantage to provide an improved process for the production of terpolymers of carbon monoxide, ethylene and secondary olefinically unsaturated hydrocarbon.